System and method for phase calibration of an antenna array

1. A system for phase calibration of an antenna array comprising at least two antenna elements, the system comprising: a device under test comprising the antenna array, a plane wave converter, and a phase measuring unit, wherein the device under test is configured to transmit or receive a test signal with spatially dependent phase, wherein the plane wave converter is configured to convert the test signal with spatially dependent phase into a signal with constant phase, and wherein the device under test or the phase measuring unit is configured to derive calibration values for the phase calibration of the antenna array from the signal with constant phase.

2. The system according to claim 1 , wherein the device under test comprising the antenna array which comprises the at least two antenna elements is configured to sweep the test signal through different phases stepwise, or wherein the phase measuring unit is configured to sweep the test signal through different phases stepwise.

3. The system according to claim 2 , wherein each phase-sweep step is triggering a sample in the device under test or in the phase measuring unit.

4. The system according to claim 2 , wherein the device under test or the phase measuring unit is configured to derive several transfer coefficients from each phase-sweep step with corresponding measured phase values.

5. The system according to claim 4 , wherein the several transfer coefficients form the basis for deriving calibration values with the aid of the device under test or the phase measuring unit.

6. The system according to claim 1 , wherein a temperature difference of the at least two antenna elements against each other is lower than 7 degrees Celsius, preferably lower than 5 degrees Celsius, most preferably lower than 3 degrees Celsius.

7. The system according to claim 2 , wherein while stepwise sweeping the phase of the test signal, a temperature difference of the at least two antenna elements against each other is lower than 7 degrees Celsius, preferably lower than 5 degrees Celsius, most preferably lower than 3 degrees Celsius.

8. The system according to claim 1 , wherein a temperature based phase shift of the at least two antenna elements against each other is lower than 7 degrees phase shift, preferably lower than 5 degrees phase shift, most preferably lower than 3 degrees phase shift.

9. The system according to claim 2 , wherein while stepwise sweeping the phase of the test signal, a temperature based phase shift of the at least two antenna elements against each other is lower than 7 degrees phase shift, preferably lower than 5 degrees phase shift, most preferably lower than 3 degrees phase shift.

10. A method for phase calibration of an antenna array of a device under test comprising at least two antenna elements, the method comprising the steps of: transmitting or receiving a test signal with spatially dependent phase with the aid of the device under test, converting the test signal with spatially dependent phase into a signal with constant phase with the aid of a plane wave converter, and deriving calibration values for the phase calibration of the antenna array from the signal with constant phase with the aid of the device under test or a phase measuring unit.

11. The method according to claim 10 , wherein the method further comprises the step of sweeping the test signal through different phases stepwise with the aid of the device under test comprising the antenna array which comprises the at least two antenna elements, or wherein the method further comprises the step of sweeping the test signal through different phases stepwise with the aid of the phase measuring unit.

12. The method according to claim 11 , wherein each phase-sweep step is triggering a sample in the device under test or in the phase measuring unit.

13. The method according to claim 11 , wherein the method further comprises the step of deriving several transfer coefficients from each phase-sweep step with corresponding measured phase values with the aid of the device under test or the phase measuring unit.

14. The method according to claim 13 , wherein the several transfer coefficients form the basis for deriving calibration values with the aid of the device under test or the phase measuring unit.

15. The method according to claim 10 , wherein a temperature difference of the at least two antenna elements against each other is lower than 7 degrees Celsius, preferably lower than 5 degrees Celsius, most preferably lower than 3 degrees Celsius.

16. The method according to claim 11 , wherein while stepwise sweeping the phase of the test signal, a temperature difference of the at least two antenna elements against each other is lower than 7 degrees Celsius, preferably lower than 5 degrees Celsius, most preferably lower than 3 degrees Celsius.

17. The method according to claim 10 , wherein a temperature based phase shift of the at least two antenna elements against each other is lower than 7 degrees phase shift, preferably lower than 5 degrees phase shift, most preferably lower than 3 degrees phase shift.

18. The method according to claim 11 , wherein while stepwise sweeping the phase of the test signal, a temperature based phase shift of the at least two antenna elements against each other is lower than 7 degrees phase shift, preferably lower than 5 degrees phase shift, most preferably lower than 3 degrees phase shift.